The present invention relates to hydraulic anti-vibration sleeves, used in particular in automobiles.
More particularly, the invention relates to a hydraulic anti-vibration sleeve comprising:
a rigid inner strength member extending parallel to a central axis,
a tubular, rigid outer strength member surrounding the inner strength member and the central axis,
an elastomer body connecting the inner and outer strength members together and forming at least two hydraulic chambers communicating with one another via a throttled passage, said hydraulic chambers and said throttled passage being filled with a liquid,
and an intermediate member which is fitted around the elastomer body and clamped between the elastomer body and the outer strength member, the throttled passage being at least partially bounded by the intermediate member, and said intermediate member extending in a circumferential direction around the central axis between the two hydraulic chambers.
Document EP-B-0 656 487 discloses a hydraulic anti-vibration sleeve of this type, in which the intermediate member forms a belt which completely surrounds the elastomer body and which is made out of two rigid parts. When assembling the intermediate member to the elastomer body, the two portions forming the elastomer body must be snap-fitted together around the elastomer body.
Although this prior anti-vibration sleeve gave perfect satisfaction in use, this assembling process proved cumbersome and sometimes difficult to carry out, since the two portions of the intermediate member had to be snap-fitted together while being clamped around the elastomer body.
An object of the present invention is to remedy this drawback.
To this end, according to the invention, said intermediate member is a C-shaped, unitary, resilient member and is snap-fitted around the elastomer body, said intermediate member extending in a circumferential direction around the central axis on an angle of at least 200xc2x0, said intermediate member thus being sufficiently elastically clamped around the elastomer member so that said intermediate member be securely fixed on said elastomer member before the outer strength member is fitted on said elastomer body.
Thanks to these dispositions, the assembling process of the intermediate member to the elastomer body is very simple to carry out, since it does not imply assembling together several pieces around the elastomer body.
Further, the present invention also renders the global assembling process of the sleeve more reliable, since the intermediate member is held by itself around the elastomer body, so that there is virtually no risk that said intermediate member be disassembled from the elastomer body between the step of snap-fitting said intermediate member around the elastomer body and the step of tight fitting the outer strength member around the elastomer body.
In advantageous embodiments, one may further use one and/or other of the following arrangements:
the intermediate member is made of plastic material;
the elastomer body includes first and second arms which separate the two hydraulic chambers, the intermediate member including:
a connecting portion which is clamped between the first axial arm and the outer strength member,
and two end portions which are linked together by said connecting portion and which extend respectively in the two hydraulic chambers;
at least one of the end portions of the intermediate member includes an abutment portion which protrudes radially inwardly in one of the hydraulic chambers and which is adapted to cooperate with the elastomer body for limiting relative radial movements of the inner and outer strength members;
the elastomer body is over-molded on a rigid armature which includes two annular bushings interconnected by at least an axial strut extending in the first axial arm of the elastomer body, said connecting portion of the intermediate member being radially clamped between said axial strut and the outer strength member;
each of said end portions of the intermediate member is radially clamped between the two bushings of the rigid armature and the outer strength member;
each of said two end portions of the intermediate member extend up to a free end which is close to the second axial arm of the elastomer body;
the connecting portion of the intermediate member is tightly fitted in a groove formed in the first axial arm of the elastomer body;
said end portions are larger than the connecting portion parallel to the central axis and said throttled passage forms sinuosities at least in one of said end portions;
the intermediate member is made out of a single piece and includes an arcuate groove which is open toward the outer strength member, said intermediate member being in tight contact with the outer strength member so that said groove and said outer strength member entirely bound the throttled passage;
the intermediate member includes a tube which entirely bounds the throttled passage;
the elastomer body includes first and second arms which separate the two hydraulic chambers, said tube being clamped between the first axial arm of the elastomer body and the outer strength member, and wherein the intermediate member further includes two end portions which are linked together by said tube and which extend respectively in the two hydraulic chambers;
said end portions of the intermediate member are over-molded on said tube;
said intermediate member extends in a circumferential direction around the central axis on an angle of at most 340xc2x0.